A conventional linear motor includes a stator provided with permanent magnets and a mobile element provided with at least one excitation coil. Such a linear motor, for example, is described in European Published Patent Application No. 0 871 284, where it is used in an X-Y table. The stator includes a magnetic yoke member on which are positioned a series of juxtaposed magnets of alternating north-south polarity. It is important that the magnets be carefully positioned in parallel to one another and that a constant pole pitch be maintained. These magnets are, in general, affixed by gluing. When these magnets are brought in proximity with the magnetic yoke member, the force of attraction created between the yoke and the magnets may make precise positioning of the magnets on that yoke difficult except on an assembly line having special equipment that may be costly and cumbersome. The operation of gluing magnets on a magnetic yoke member is almost impossible manually.
Gluing magnets on a motor yoke member may present a major problem whenever that yoke is an integral part of the equipment frame in which the motor is integrated. Attachment of the magnets at the installation site may be preferable and desirable, e.g., for linear motors of a certain length.
A robot may be used to perform this operation of positioning and affixing magnets to the magnetic path of a linear motor. This solution may have the disadvantage of requiring a significant investment and a great deal of time to glue all the magnets.
On the other hand, the use of tools to install magnets along a horizontal path is conventional. This method, therefore, requires horizontal access throughout the length of the magnetic path to install the magnets, which is an impediment but always possible. Moreover, the tooling used for this horizontal installation is fragile and ill suited to gluing techniques.
It may be possible to glue magnets that have not yet been magnetized, the actual magnetization of the magnets occurring after they have been glued to the magnetic yoke member of the motor. If, in this case, gluing of the magnet occurs without problems, because of the absence of magnetic attraction, this solution may nevertheless require a very considerable investment, e.g., with respect to the magnetization tooling, and also may require lengthy cycle time for each magnet.